Expression Level of Transcription Factor ART1 Is Responsible for Differential Aluminum Tolerance in Indica Rice

Rice is the most aluminum (Al)-tolerant species among the small grain cereals, but there are great variations in the Al tolerance between subspecies, with higher tolerance in japonica subspecies than indica subspecies. Here, we performed a screening of Al tolerance using 65 indica cultivars and found that there was also a large genotypic difference in Al tolerance among indica subspecies. Further characterization of two cultivars contrasting in Al tolerance showed that the expression level of ART1 (ALUMINUM RESISTANCE TRANSCRIPTION FACTOR 1) encoding a C2H2-type Zn-finger transcription factor, was higher in an Al-tolerant indica cultivar, Jinguoyin, than in an Al-sensitive indica cultivar, Kasalath. Furthermore, a dose-response experiment showed that ART1 expression was not induced by Al in both cultivars, but Jinguoyin always showed 5.9 to 11.4-fold higher expression compared with Kasalath, irrespectively of Al concentrations. Among genes regulated by ART1, 19 genes showed higher expression in Jinguoyin than in Kasalath. This is associated with less Al accumulation in the root tip cell wall in Jinguoyin. Sequence comparison of the 2-kb promoter region of ART1 revealed the extensive sequence polymorphism between two cultivars. Whole transcriptome analysis with RNA-seq revealed that more genes were up- and downregulated by Al in Kasalath than in Jinguoyin. Taken together, our results suggest that there is a large genotypic variation in Al tolerance in indica rice and that the different expression level of ART1 is responsible for the genotypic difference in the Al tolerance.

Inhibitory Effect of Several Mangifera indica Cultivar Leaf Extracts on the Formation of Advanced Glycation End Products (AGEs)

As a part of our ongoing research to find novel functions in mango leaves, we have reported that the methanolic extract of pruned old dark green mango leaf (Mangifera indica ‘Irwin’) exhibited inhibitory effects on the formation of advanced glycation end products (AGEs) in nonenzymatic glycation of albumin. The purpose of this study was to find other mango cultivars with more potent activity in this regard. We examined the inhibitory effect of seventeen mango (Mangifera indica) cultivar leaf extracts on AGEs formation. We also investigated the relationship between the inhibitory activity of the extracts and the contents of their active components, 3-C-β-D-glucosyl-2,4,4’,6-tetrahydroxybenzophenone (1), mangiferin (2) and chlorophyll (3). On the basis of the evaluation of the inhibitory activity of mango cultivar leaf extracts, the HPLC determination of the contents of 1 and 2, and the spectrophotometric determination of 3, it was found that almost all extract showed a significant activity, and the content of 2 and 3 detected in each was similar. In contrast, AGEs formation inhibition tended to be higher as the content of 1 in the leaf extracts increased. This is the first report of phytochemical analysis of compounds 1, 2 and 3 in various cultivars of mango leaf. From the phytochemical point of view, these results suggest that the pruned leaves of any cultivar of Mangifera indica except ‘Chiin Hwang No. 1’ and ‘Kyo Savoy’ may be useful for the preparation of natural ingredients with inhibitory activity of AGEs formation.

GC-MS ANALYSES OF ESSENTIAL OILS OF THREE VARIETIES OF Mangifera indica

Mangifera indica or commonly known as mango, is one of the 30 species of Mangifera genus from the family of Anacardiaceae. The fruit of M. indica is consumed for its antioxidant and health promoting activities in addition to its exotic flavor and texture. The present study was aimed to comparatively analyze the volatile constituents in the peel and pulp of M. indica cultivar Falan, Water Lily and Chok-anan. The mango peel and pulp were subjected to hydrodistillation using Clavenger type apparatus and the essential oils obtained were analyzed using GC-MS. There were 32 compounds identified in the essential oils of peel and pulp of three M. indica L. cultivars. Falan mango has the highest monoterpenes hydrocarbon composition in the essential oils of peel and pulp with 30.67% and 45.65%, respectively, whereas the essential oils of Water Lily mango are mainly dominated by the presence of sesquiterpenes hydrocarbon in both peel and pulp with 50.75% and 67.11%, respectively. The essential oils of Chok-anan mango are mainly consist of miscellaneous compounds in the peel and pulp with 22.56% and 44.1%, respectively. 4-Carene, b-caryophyllene, a-terpinolene, cyclohexadecane and n-hexadecanoic acid were the major volatile constituents in the essential oils of the three mango varieties.